Cast iron 250Х25НТ
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Cast iron 250X25NT
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Designation
| Name | The value |
|---|---|
| Designation GOST Cyrillic | 250Х25НТ |
| Designation GOST Latin | 250X25HT |
| Transliteration | 250H25NT |
| The chemical elements | 250Cr25НTi |
Description
Cast iron 250Х25НТ used: for the production of castings of parts operating under conditions of abrasive wear (sand and gravel pumps, hydrocyclones, classifiers, flotation machines, linings of mills, etc.), as well as in aggressive environments or at high temperatures (up to 1000°C).
Alloy brand 250Х25НТ used for the production of parts of any configuration with a wall thickness up to 150 mm. When the parts in aggressive environments or at high temperatures should be preferred alloys 250Х25Т and 250Х25НТ with carbon on the bottom and chrome on the upper level.
Castings must allow for their application in macroclimatic regions with moderate and cold climate indoors (climatic version Y, CL, a resolution category 4 according to GOST 15150).
Note
Wear-resistant alloy (cast iron).
Standards
| Name | Code | Standards |
|---|---|---|
| Castings with special properties (cast iron and steel) | В83 | TU 48-0114-57-90 |
Chemical composition
| Standard | C | S | P | Mn | Cr | Si | Ni | Fe | Ti |
|---|---|---|---|---|---|---|---|---|---|
| TU 48-0114-57-90 | 2.3-2.8 | ≤0.05 | ≤0.05 | 0.5-0.8 | 23-28 | 0.3-1 | 0.7-1 | The rest | 0.1-0.2 |
Fe is the basis.
Technological properties
| Name | The value |
|---|---|
| Features of production | Smelting can be done in induction and electrical arc furnaces with acid or basic lining. It is recommended that castings be annealed prior to mechanical processing and normalization (hardening in the air) before operating under conditions of abrasive wear. The recommended heat treatment regime: Annealing at 750-800 °C; the normalization with 1050-1100 °C. the hardness of castings in as-cast 45-50 HRC after annealing 35-45 HRC, after normalization - 55-62 HRC. Profit casting should be done in private legkodelimae, with a supply of metal in the profit and calculate their normals for steel casting. |
| Features of heat treatment | The heating of the parts under heat treatment is conducted with an initial temperature not more than 200 °C at a speed of 60-70 °C per hour to 600 °C. At this temperature the cage is aged for 1-2 hours, then the heating rate can be increased to 100-150 °C per hour. At the maximum temperature of the heat treatment is aging at the rate of 1 hour for every 25 mm biggest casting thickness. Heating and holding furnace of the casting can be carried out by the regime of heat treatment of steel 110G13L (or with parts made of this steel) but with air cooling. With the normalization, it is recommended to remove items from the cart immediately after rolling it out of the oven, which allows to obtain the highest wear resistance. When annealing is the cooling of the casting with the furnace to 200 to 400 °C. |
| Defect welding | Corrections of defects by welding. Technology and welding conditions should guarantee the usefulness of fixed casting in their operating conditions. For the welding of working surfaces of parts the following are recommended types of electrodes (GOST 10051): EN-У30Х28С4Н4-50, AL-80Х4СГ, EN-У30Х25РС2Г-60, EN-У30Х23Р2с2ТГ-55. Wear parts castings can be brewed type electrodes EA-2 according to GOST 10052 or close to them in composition. |
| Machining by cutting | Optimal results when machining castings makes use of tools made of hard alloys brands НК8 and НК6М. The coefficient of machinability after annealing is 2.0. |
